[nanomsg] Re: Broadcast protocol
- From: Nico Williams <nico@xxxxxxxxxxxxxxxx>
- To: nanomsg@xxxxxxxxxxxxx
- Date: Wed, 11 Sep 2013 12:04:06 -0500
On Wed, Sep 11, 2013 at 04:13:22PM +0300, Paul Colomiets wrote:
> 1. There are many watchers
>
> 2. Watcher subscribes to a channel at the start
>
> 3. When subscribing watcher gets current data on a channel
>
> 4. When channel data changes, all its watchers get new value
>
>
> Combination of pubsub and reqrep can't be used here, because when pubsub
> temporarily disconnects some updates can be lost.
Sounds like pubsub with reliability -- I'd call it "reliable pubsub" :)
Should be possible to implement as a layer above pubsub that:
- adds sequence numbers to messages,
- keeps N messages buffered for making them available via reqrep,
- and has subscribers detect message loss and respond by requesting the
missing messages.
You might want to add a heartbeat message so that subscribers can
distinguish long runs of message loss from infrequent publication of new
data (publishers should publish the heartbeat interval / frequency).
Note that this is a building block for some secure pubsub protocols as
well.
Nico
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